If you have a 1-cup measuring cup, filling it up to the two-thirds mark is exactly what you need. No fractions, no stress. Just pour until you hit that line.
But what if you only have a 1/3 cup measure? Easy: you use two of them. Two 1/3 cups equal exactly 2/3 of a cup. See? You already knew how to do this.
It’s the same as saying, “I’ll take two slices from a pizza cut into three equal slices.” You don’t need a calculator for pizza, so why need one for flour?
